Colorado wildlife overpass cuts vehicle-animal collisions by 91 percent

A wildlife overpass across Interstate 25 between Denver and Colorado Springs has cut vehicle-animal collisions by 91 percent in the ten months since it opened, according to a report released this week. Before the bridge, the Colorado Department of Transportation counted an average of one wildlife-vehicle crash per day in the corridor, which runs through a region known for heavy movement of large game.

The structure is the largest of nearly 20 wildlife crossings now under way in the United States. It spans six lanes of traffic, connects 39,000 acres of habitat on the two sides, and measures 200 feet wide by 209 feet long, grass-covered with gradually sloped entrances. Elk, bears, pronghorn and northern leopard frogs have been tracked on the overpass; the wider corridor records mule deer, coyotes, rabbits and the threatened Preble's meadow jumping mouse. Brandon Marette, a wildlife biologist with Colorado Parks and Wildlife, was sent a photograph by the transportation department of an elk mother taking her calf under the interstate, through the smaller crossings that serve animals willing to use them.

The overpass exists because the animals refused the alternatives. Elk and pronghorn prefer big open structures where they can see for miles in each direction, said Chuck Attardo, the department's environmental manager; tunnels and underpasses restrict their movement and leave no room for antlers. Research cited in the report shows overpasses can nearly eliminate wildlife-vehicle accidents, which injure and kill drivers as well as animals, and often pay for themselves by preventing costly crashes.

The project received $22 million in federal funding and $8 million from the state, and was completed, officials say, for $15 million. The department now hopes to build more crossings across Colorado.

Pronghorn moving between Trinidad and Greenland had been looking for a place to cross I-25 for decades. After the overpass opened, they were recorded on video crossing to the west side — the first time in decades.